Hydrazine hydrate (1:1) → 6-(4-Hydroxyphenyl)-5-methyl-4,5-dihydropyridazin-3(2H)-one

Participants

Reaction Conditions

Reaction Steps

A 1 1 three-necked round-bottomed flask equipped with a condenser connected to a gas inlet, a glass rod air driven stirrer and a thermometer was charged with 63.8 g, (306 mmol) of (±)-3-(4'-hydroxybenzoyl)-3-methylpropanoic acid from Example H and 2-propanol (400 ml) at 40° C. The solution was placed under an atmosphere of nitrogen and heated to 65° C. Then hydrazine monohydrate (45 ml, 2.2 mol) was added dropwise over 10 min. The reaction mixture was heated to 80-81° C. (reflux), stirred for 1 hour then slowly cooled to 3° C. over 1 hour with gentle stirring. The formed precipitate was collected by suction filtration, triturated in a 1 L beaker with deionized water (300 ml) at 23° C. for 2 hrs and collected by suction filtration. The solids were dried to constant weight in an air oven (90° C.) to provide 51.9 g (83.5%) of pure (±)-4,5-dihydro-6-(4'-hydroxyphenyl)-5-methyl-3(2H)-pyridazinone, m.p. 268°-273° C.

Provenance & Evidence